Pressure atomizing oil burner with a built-in combustion chamber



y 1950 J. A. LOGAN EI'AL 2,516,063

PRESSURE ATONIZING on. BURNER WITH A BUILT-IN comaus'rxou CHAMBER FiledAug. 19, 1948 M 3 Sheets-Sheet 1 J W1. a1

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12 1 11 il qj v) 35 y a I 37 I ff" 1 I PW i. k 36 1a f Ll 22 -26 3INVENTOR5 Jose/u! Atom/1m filt'l/M'DMC'Ml/AMYE +7/14L ATTORNEYS J y 8,1950 J. A. LOGAN EIAL 2,516,063

PRESSURE ATOIIIZING OIL BURNER wm-x A BUILT-IN comaus'rxon CHAMBER FiledAug. 19, 1948 3 Sheets-Sheet 2 asv l |3 |E 23' 27 7 as 37 36 22 I l l la ATTORNEYS Patented July 18, 1950 PRESSURE ATOMIZING OIL BURNER WITH ABUILT-IN COMBUSTION CHAMBER Joseph A. Logan, Hadley, and Richard M.Cochrane, West Springfield, Mass, assignors to Gilbert & BarkerManufacturing Company, West Springfield, Mass, at corporation ofMassachusetts Application August 19, 1948, Serial No. 45,068

4 Claims. 1

This invention relates to an improved oil ments common in the gun typeburner, but to add a combustion chamber built out of sight inside theair tube element, and provide added elements and arrangements providingin their combination for an improved mode of operation. The improvedoperation is caused by the way the oil and air are controlled for mixingand burning in the built-in combustion chamber.

One form of gun type burner having a builtin combustion chamber is shownin the Logan Patent No. 2,411,048, dated November 12, 1946. Such burnerhas some points in common with the present invention, as a comparisonwill show, but the points of difference are significant as will bebrought out with respect to features of operation.

An illustrative example of the invention, with some variations indetail, is shown in the accompanying drawings, in which:

Fig. l is a front elevational view of an oil burner embodying theinvention, certain parts of the fan housing being broken away to showinterior construction;

Fig. 2 is a fragmentary sectional elevational view taken on line 22 ofFig. 1;

Fig. 3 is a sectional plan view taken on the line 3-3 of Fig. 2;

Figs. 4, and 6 are cross sectional views taken on the lines 4-4, 5-5,and 66, respectively of Fi 2;

Fig. 7 i a fragmentary sectional view, taken similarly to Fig. 3 andshowing a modification in the construction of the combustion-chamber;

Fig. 8 is a cross-sectional view taken on the line 8-8 of Fig. '7;

Fig. 9 is a fragmentary sectional elevational view, taken similarly. toFig. 2 and showing another modification in the construction of thecombustion-chamber;

Fig. 10 is a cross sectional view taken on the line Ill-I0 of Fig.9;

Fig. 11 is a sectional plan view taken on the line |l--ll of Fig. 9: and

Fig. 12 is a large scale cross sectional view of a pressure regulatingvalve especially adaptedfor use in the oil feeding system of the burner;

Referring to these drawings and first to Fig. 2 thereof, the burnerincludes a hollow casting I, suitably supported, as by a pedestal 2,from the fioor and providing in its upper portion a housing 3 for a fan4 and in its lower portion a horizontally-disposed cylindrical passage5, which receives air from fan 4 through the opening 6. The rear end ofpassage 5 is closed by a cover I, secured to casting l by screws 8.Secured at its flanged inner end to casting i by screws 9 and mountedco-axially of and as an extension of passage 5 is an air tube l0.Suitably fixed in the outer end of tube I0 is an annular ring ll, havinga seat to receive with a sliding fit the outer end of a tube l2, locatedwithin and co-axially of air tube It. The outer end of tube I2 is open.Its inner end is closed by a circular disk I3, suitably fixed thereto.Fixed to this disk by screws H is a member 15. The disk also has twohubs to which are fixed, one in each, two rods l6 (Fig. 3). These rodsextend rearwardly in the passage 5 inspaced parallel relation, one neareach side of the passage, and their rear ends are outturned as at 11 andengaged, one in each, of two recesses formed at diametrically-oppositepoints in the peripheral wall of passage 5. The tube i2 is thussupported at its front end by ring H and at its rear end by rods 16. Byremoving cover I, access is had to the ends ll of these rods 30 thatsuch ends may be pulled out of the recesses, in which they are engaged,and then pulled rearwardly to draw out the tube l2 and all the partsmounted thereon, for inspection, adjustment or repair. The tube 12 maybe replaced by pushing it inwardly through passage 5 into air tube l0until its outer end engages in ring ll, then engagin the ends H in theirrecesses and then replacing cover I.

The inner tube I! (Fig. "2) forms within it a combustion chamber l8,into which all the air for combustion is introduced to mix with a sprayof atomized oil, emitted from a pressure-atomizing nozzle I9, locatedco-axially of the tube and chamber. This nozzle is supplied with oil atsuitable pressure by a pump 20 (Fig. 1) through a pipe 2| (Figs. 1 and2). which enters the rear end of passage 5 (Fig. 2) v and extendsforwardly therein for connection to the rear end of the nozzle support22. The latter has, a passage 22' (Fig. 6) therethrough, allowingcontinuous communication between pipe 2| and the nozzle I3 carried bythe front end of the support. This nozzle support 22 is of hexagonalcross sectional shape (Figs. 4, 5 and 6) and is held frictionally in atube .23, which in turn is held irictionally in the member I5 and has anenlarged head 23' at its inner end. Six passages 24 are left betweensupport 22 and tube 23 to connect air supply passage I to the combustionchamber l3 and allow streams of air to flow parallel to the axis of thenozzle and chamber l8. The support I5 also has fixed therein a pair ofinsulators 25 (Fig. 3) supporting, one in each, ignition electrodes 23(Fig..

1), located. to ignite the spray emitted from nozzle l3. Theseelectrodes are connected by wires 21 (Fig. 3) to the high tensionterminals 23 of an ignition transformer, contained within a casing 29.fixed to casting I. The nozzle and electrodes can be removed separatelyfrom the combustion chamber by removing screws I4, which allows memberI5 to be separated from disk I3 and removed with the nozzle andelectrodes which it supports. The head 23, when engaged with the memberI5 as shown, locates the tube 23 properly inside tube I2. The nozzle I3is properly located in tube 23 when the inner end of its support 22 liesflush with the inner end of head 23'.

The combustion chamber I8 occupies the necessary to complete combustion.The burning mixture rotates around the combustion chamber as it movestoward the outlet end. This rotating mixture creates a vortex. Thecreation of the vortex would ordinarily result in the production or apartial vacuum in the space around the nozzle, as a result of whichthere would be a greater part of the interior of th tube I2. However,the rear portion 30 of this tube is separated from the rest by apartition 3| of frusto-conical form and having a large central opening32, through which atomized oil and some air are admitted to thecombustion chamber. Most of the air for combustion is admitted throughthe periphery of tube I2 from a jacket 33 which is formed between thetubes [0 and I2, is closed at its front end by ring II and is open atits rear end to the air supply passage 5. Near the inner end of tube l2are a circular series (eight as shown) of angularly-spaced inletopenings 34 in the form of slots, which extend parallel with the axis oftube l2 and which allow air from jacket 33 to enter the chamber 30.These openings 34 are best shown in Fig. 5. They are formed by I2. Theseslots are arranged in three longitudinally-spaced circular series, eachseries comprising a plurality, as three, of angularly-spaced slots whichpartially overlap the slots of the adjacent series. The slots in oneseries are shown as staggered with relation to the slots in the adjacentseries, as will be clear from Figs. 2 and 4. Each slot 36 is formed, bypunching out vane parts 31 to lie tangentially, or substantially so withtendency for the flame to move toward the nozzle. Thelongitudinally-directed streams of air, issuing from the severalpassages 24, prevent the formation of such partial vacuum and counteractsaid tendency, acting to keep the flame away from the nozzle to avoidcarbon deposits thereon. The revolving streams of air in the innerchamber 30 also help to move the flame away from the nozzle as suchstreams pass opening 32 of disk 3|. Such last-named streams sweep pastthe ignition electrodes 23 as they pass to opening 32 and help keep themfree of carbon deposits. They also serve to feed air to the oil spray atand near the location where ignition occurs and these streams, movinginwardly as they approach the opening 32 in ring 3|, will blow thespark, which is produced between the electrodes, into the spray. Byrotating the air around the flame, the latter is materially shortened.Most of the combustion occurs within the chamber l3, for example, nomore than a quarter of the length of the flame in the usual operationextends outside the combustion chamber. The streams of air sweep theinner wall of the combustion chamber, tending to keep the oil or flamefrom impinging thereon and, by so doing, preventing the transfer of heatby conduction from the flame to tube l2 and thereby keeping thetemperature of the wall of the chamber within reasonable limits. Thiswall will still'be hot enough in normal operation to vaporize the oil.

The arrangement of air-feeding slots may be varied within substantiallimits although the form shown in Figs. 2, 3 and 4 is now believed to bethe best and is at present preferred. In Fig. '7, a tubular member I2 isconstructed like the member l2 with the exceptionthat the slots 33leading into the combustion chamber each extend substantially from oneend to the other of this chamber. As shown in Fig. 8, there is acircular series of six slots 33, angularly-spaced one from the other.The member I2 has also a series of slots 34, leading, as formerly, intothe inner chamber 30, in which the nozzle I9 is located.

In Fig. 9 there is shown a tubular member I2 having like the member l2,-three sets of slots 35, each set being axially-spaced one from anotherand consisting of a circular series of angularlyspacedlongitudinally-extending slots. The difference here is in theconstruction of the rear wall of the combustion chamber Ill and theomission of the annular partition ring 3|. The rear wall 33 is offrusto-conical form, terminating in a central, hollow cylindrical hub40, in which the cylindrical support 4| for nozzle I3 is mounted andflxed as indicated. The wall 33 (Fig. 11) also has twodiametrically-opposed hubs 42 on its outer periphery in which are fixedthe described supporting rods I6. Fixed to these asiaooa rods, is across piece 43 in which is mounted the nozzle support 41 and theinsulators 25. The electrodes 26 pass through and are suitably insulatedfrom the rear wall. The frusto-conical inner wall 39 (Figs. 9.and 10) isprovided with a series of angularly-spaced slots 44. These radiate fromhub 40 and are so formed as to admit air in streams which whirl aroundthe rear end of the chamber and the electrodes and nozzle II and, movingforwardly, tend to keep the oil away from the nozzle and the electrodes.

The fan 4 and pump 20 (Fig. 1) are driven by an electric motor 45, fixedas indicated to one side wall of the fan housing with its rotor shaft 46extending into the interior of the casing to receive fan 4, which isfixed thereto as indicated. The oil pump is supported from a member 41connected by arms 48 to the housing I. The pump is preferably drivenfrom shaft 46 through the intermediary of a time delay clutch. Anexample of one suitable clutch will be found in Logan Patent No.1,985,934, dated January 1, 1935. An improved form of clutch isdisclosed in the Theodore J. Mesh Patent No. 2,485,211, dated October18, 1949. This improved form of clutch is the form at present preferred.The

driving and driven clutch drums of this improved clutch are shown at 49and 50 as respectively fixed to the motor shaft 45 and a driven shaftwhich is connected by a flexible coupling 52 to the shaft 53 of pump 20.The carrier for the centrifugal weights is shown at 54. This type ofclutch can be adjusted to delay the start of the pump for substantialintervals after the fan has started, say several seconds, and isarranged to prevent the pump starting until the fan has acquired fullspeed. The purpose is to establish the full flow of air at the desiredvelocity before any oil is emitted from the nozzle 19. 4

Fig. 1 shows the precision adjustment for the air flow. A shutter 55 ismovable toward or away from the inlet opening 56 in the fan housing 3 bymeans of a screw 51. This screw has its inner end rotatably mounted inan end wall of housing I and its outer end rotatably mounted in member4'1. A spring 58 on the screw acts between member 47 and a washer 59,held by a pin to the screw, to hold the head of the screw against theouter face of member 41. The latter has fixed thereto one end of a rod60, the other end of which passes through the shutter and prevents itfrom rotating, when screw 51 is turned. The shutter is encompassed by asheet metal casing 51 having slots 62 of suflicient aggregate area toadmit all the air that will ever be needed for operation of the burner.

The pressure-regulating meansfor controlling the pressure of the oilsupplied by pump 20 to atomizing nozzle I9 is in this case built intothe casing of the pump itself. The construction is shown in Fig. 12. Inthe lower part of the pump casing is a cylindrical bore 63, in thecentral portion of which is fixed a sleeve 64. The ends of bore 53 areclosed by plugs 65 and $6, threaded into the bore and terminating withtheir inner ends axially-spaced from the adjacent ends of sleeve 64,forming spaces 51 and 68. A passage 59 leads from the discharge side ofpump 20 to space 87. The space 58 is connected by a passage 10 to theintake side of the pump. Slidably mounted in sleeve 64 is a hollowpiston Ii, having fixed to one end thereof a, valve I2, adapted toengage a seat on plug 55 and close the outlet port I3, which leads tothe nozzle feed pipe 21.

-A spring 14, acting between an adjustable abutment l5 threaded intoplug 55 and the piston ll,

yielding-1y holds valve 12 on its seat to close the outlet ll. Pressureof the pumped oil acts on the piston ll against the force of spring 14,and an additional force to be described, in a direction such as to movevalve 12 from its seat. The sleeve 54 has formed in its internalperipheral wall a circumferential groove 15, which is connected by apassage TI to the pressure space 51. A hole 10 is provided through theperipheral wall of piston II, which, when valve I2 is closed, is closedby the internal peripheral wall of sleeve 64. After the valve 12 hasopened and the pressure has built up to a predetermined degree, thepiston II will be moved rearwardly until the hole 18 in the pistonregisters with groove 16, Oil from the pressure side of the pump andspace 51 can then pass into the hollow piston and thence to space 58 andpassage III to the suction side of pump 20. Oil will be thus by-passedto keepthe pressure of the pumped oil from exceeding a predeterminedminimum, say for example 50 pounds per square inch. The structure thusfar described. is that of a conventional pressure-regulating valve.

This conventional structure is preferably modified by the addition ofmeans for placingan additional load on the valve in order to make itnecessary to produce a higher pressure on the valve to open it than isthereafter necessary to keep the valve open. It is for example desiredto make the pressure necessary to open valve 12 considerably higher thanthe pressure at which bypassing of 011 takes place through the pistonvalve described, whereas in the conventional arrangement the burneroutlet valve, corresponding to 12, wouldopen at a pressure lower thanthat at which by-passlng of oil takes place. One way of securing theadditional loading on valve I2 is to provide a circumferential groove 19in a stem fixed to piston 11, and to provide a plurality ofspring-pressed balls 8| to engage in this groove, when valve 12 isclosed. Each ball 8| and its spring 82 may be arranged in a tube 83,fixed radially in plug 65. The seat 84 for each spring 82 is threadedinto an opening in plug 55 to secure adjustment of the force of thespring and the outer end of such-opening is normally closed by aremovable plug 85. A removable plug 86 allows access for adjusting theseat 15 to vary the force of spring 14.

The springs 82, pressing the balls Bl into the groove I9, provideresistance to initial opening movement of valve 12, in addition to thatprovided by spring 14. This additional resistance, however, is removedafter the valve has opened and moved a short distance away from itsseat. As long as the balls 8| are engaged in the groove 19, there is anadditional resistance to the valveopeningmovement. However, when theballs are completely disengaged from the' groove, as they will be afterthe valve moves away from its seat a distance equal to half the width ofthe groove, this additional resistance will for all practical purposesbe removed because the balls will then ride freely on the smoothperipheral surface of stem 89 without presenting any substantialresistance to movement of the valve. The practical effect of thisarrangement is that, on starting of the burner, the oil may be atomizedinitially at a substantially higher pressure than that for which thevalve spring 14 is set and this effect may be utilized to advantage inthis particular burner as will be later described.

It is to be noted that the regulating valve described may be convertedto operate in the conventional way, if necessary or desired. The stem 766- may be removed with a screw driver after cover 86 is removed, andthis will free the valve 12 of the additional loadingmeans.

The pressure-regulating valve with the additional loading means thereforis separately shown and claimed in the Joseph A. Logan Patent No.2,451,681, dated October 19, 1948.

The pump 20 maybe of any suitable type and an example of one suitabletype will be found in Wahlmark Patent No. 2,309,683, dated February 2,1943. This patent also shows the pressure regulating valve structure(without the additional valve-loading means) and the relationship of it.to the pump structure.

In the operation of the burner of this invention, where a pressureatomizing nozzle, such as I9, is operated at substantially less than itsrated oil pressure to secure a rate of flow much less than that forwhich the nozzle is rated, it is desirable to utilize the describedadditional loading means for the pressure-regulating valve 12. This willenable better atomization to be secured because of the higher pressureused and the burner can be started up better and more quickly in thisway. Assume as one example, that the nozzle 19 is rated at one gallon anhour, when operated at 100 pounds per square inch pressure, and that itis to be operated at 50 pounds pressure in order to secure a low rate offlow, of say .66 gallon per hour. The burner will start up at this lowpressure but it takes an appreciable time, several seconds, because theoil is not well atomized at this low pressure. Eventually, some of theoil will be vaporized by the are between the ignition electrodes andthis burning oil will vaporize more oil and full combustion willeventually ensue. The combustion, following the starting interval, isexcellent-the burner of Figs. 1 to 6 operating at 12% CO2, with 50pounds per square inch oil pressure and .66 gallon per hour oilconsumption. The starting conditions present the greatest difllculty.Therefore, it is of advantage to use the higher oil pressure for a shortinterval at the start because better atomization of oil by the nozzle isobtained with the higher pressure and ignition will occur quickly andcombustion at the start will be cleaner and better.

It is also desirable to use some form of time delay clutch to delay theflow of oil until air is flowing into the combustion chamber l8 throughthe various slots and passages at the proper rate.

The particular form of improved clutch shown in said Mesh patent ispreferred because it can be made to give a delay of several secondsafter the motor 45 and fan 4 have acquired full speed before the oilpump 20 is driven. Thus, ample time is aiforded for the establishment ofair flow, at the full rate intended, in the combustion chamber it beforeany oil is emitted from nozzle l9. With this arrangement smokycombustion at the start is avoided.

When normal air flow is established, there are streams of air thatrotate around the inner peripheral wall of combustion chamber l8, whichsweep substantially the entire area of such wall from one end to theother. These air streams tepdto rotate with them the oil that is sprayedinto them, creating a vortex. Looking from the outerend of thecombustion chamber when the burner is in operation, an annular mass offlame is seen rotating in a counterclockwise direction.

Also, an annular space may be seen between the' rotating flame and theinner wall of the combustion chamber, showing that the rotating airstreams keep the flame from direct contact with the peripheral wall ofthe combustion chamber.

8 It is not clear that this last-named space extends back for the entirelength of the combustion chamber but it does extend back a substantialdistance. It is probable that some of the oil from nozzle 19 strikes theinner peripheral wall of the combustion chamber, near the partition 3|,and is vaporized by the hot wall but except for this location, thewhirling air streams keep the flame spaced from sleeve l2. In any eventthese whirling air streams keep the temperature of the sleeve withinreasonable limits. The air, being fed to the oil in whirling streams,has the effect of materially shortening the flame. Actually close tothree quarters of the flame can be confined within the combustionchamber l 8.

With the combustible mixture whirling in the combustion chamber, therewould be a tendency to create a partial vacuum around and near thenozzle, due to the vortex and the oil spray near the nozzle might beforced back onto it and car bonize. To counteract this tendency, the sixsmall longitudinal streams of air sweep bythe nozzle l9 within tube 23and force the oil spray away from the nozzle to keep it clean. Thewhirling streams of air admitted to chamber 30 also help in thisconnection, as well as to keep the oil oil the ignition electrodes andsupply air where needed near the nozzle.

While the burner is especially characterized by providing for goodcombustion from a pressure atomizing nozzle, when operated at a'pressure much less than that at which it can be efllciently operated inthe conventional gun type burner, the burner of this invention will alsoaflord excellent combustion when the nozzle is operated at its ratedpressure. With full 'rated flow, say for example 1 gallon per hour, fromthe nozzle, the resulting flame does not appear to extend much beyondthe outer end of the combustion chamber, most of the combustionoccurring within the combustion chamber as before.

The invention thus provides an improved domestic oil burner of thepressure atomizing type, having incorporated into its structure acombustion chamber, in which the air and oil may be efiectively mixedand burned under controlled conditions to secure efficient combustion,even when the atomizing nozzle is operated at a pressure much less thanthat at which good atomization takes place, with a short flame containedfor the most part within the combustion chamber.

We claim:

1. In an oil burner, an air tube having an air inlet in its inner endand an opening in its outer end, a tubular member having a peripheralwall, an inner end wall and an open outer end, said member beingtelescoped into said air tube with its outer end adjacent the outer endof said tube and fitting said opening, the peripheral wall of saidmember being spaced from the peripheral wall of the tube to form anannular air jacket, which completely surrounds the peripheral wall ofsaid member, is closed at its outer end and communicates with said inletat its inner end, the'inner end wall of said member being exposed to theair flow in said tube; an annular ring fixed to the internal peripheralwall of said member at a location nearer the inner end wall than itsouter end and partitioning the same into inner and outer chamberscommunicating with each other through the central opening in said ring,said outer chamber constituting acombustion chamber, apressure-atomizing nozzle positioned in and substantially coaxially ofsaid inner chamber to discharge a spray of atomized oil through saidopening into the outer chamber, and ignition elecanaoes trodespositioned in said inner chamber, the pe-' ripheral wall of said memberhaving a circular series of angularly-spaced longitudinally-extendingslots opening tangentially into said inner chamber to direct whirlingstreams of air around such chamber and thence forwardly to mix with theoil spray near the nozzle and pass out through said central opening intothe combustion chamber, the peripheral wall of said member having acircular series of angularly-spaced and longitudinally-extending slotsopening tangentially into said combustion chamber, whereby the air forcombustion is whirled around the combustion chamber and around theflame, said slots being located to direct whirling streams of air intothe combustion chamber through said peripheral wall substantially fromend to end thereof for sweeping the entire inner surface of saidperipheral wall, said whirling streams of air acting to shorten theflame and confine it for the most part within the limits of thecombustion chamber.

2. In an oil burner, an air tube having an air inlet in its inner endand an opening in its outer end, a tubular member having a peripheralwall, an inner end wall and an open outer end, said member formingwithin it a combustion chamber and being telescoped into said. air tubewith its outer end adjacent the outer end of said tube and fitting saidopening; the peripheral wall of said member being spaced from theperipheral wall of the tube to form an annular air jacket, whichcompletely surrounds the peripheral wall of said member, is closed atits outer end and communicates with said inlet at its inner end; theinner end wall of said member being exposed to the air ilow in saidtube, a cylindrical tube fixed in said end wall and projecting into saidchamber in coaxial relation therewith, a support of polygonal crosssection fitted into said tube, a pressureatomizing nozzle fixed on theinner end of said support, there being between said support and tube aplurality of passages parallel with the axis of the tube, to emit air inlongitudinal streams which surround said nozzle, the peripheral wall ofsaid member having a circular series of angularly-spaced andlongitudinally-extending slots opening tangentially into said chamber,whereby the air for combustion is whirled around the combustion chamberand around the flame, said slots being located to direct whirlingstreams of air into the combustion chamber through said peripheral wallsubstantially from end to end thereof for sweeping the entire innersurface of said peripheral wall, said whirling streams of air acting toshorten the flame and confine it for the most part within the limits ofthe combustion chamber.

3. In an oil burner, an air tube having an airinlet in its inner end andan opening in its outer end, a tubular member having a peripheral wall.an inner end wall and an open outer end, said member being telescopedinto said air tube with its outer end adjacent the outer end of saidtube and fitting said opening; the peripheral wall of said member beingspaced from the peripheral wall of the tube to form an annular airjacket, which completely surrounds the peripheral wall of said member,is closed at its outer end and communicates with said inlet at its innerend; the inner end wall of said member being exposed to the air flow insaid tube; a cylindrical tube fixed in said end wall and projecting intosaid chamber in co-axial relation therewith, a support of polygonalcross section fitted into said tube, a pressure-atomizing nozzle fixedto the inner end of said support, there being between said support andtube a plurality of passages parallel with the axis of the tube, to emitair in longitudinal streams which surround said nozzle, an annular ringfixed to the internal peripheral wall of said member at a locationnearer the inner end wall than its outer end and partitioning the sameinto inner and outer chambers commimicating with each other through thecentral opening in said ring, said outer chamber constituting acombustion chamber, said nozzle being positioned in and substantiallyco-axially of said inner chamber to discharge a spray of atomized oilthrough said opening into the combustion chamber, and ignitionelectrodes positioned in said rear chamber, the peripheral wall of saidmember having a circular series of angularly-spacedlongitudinallyextending slots opening tangentially into said innerchamber to direct whirling streams of air around the chamber and thenceforwardly to mix with the oil spray near the nozzle and pass out throughsaid central opening into the combustion chamber, the peripheral wall ofsaid member having a circular series of angularly-spaced andlongitudinally-extending slots opening tangentially into said combustionchamber, whereby the air for combustion is whirled around the combustionchamber and around the flame, said slots being located to directwhirling streams of air into the combustion chamber through saidperipheral wall substantially from end to end thereof for sweeping theentire inner surface of said peripheral wall, said whirling streams ofair acting to shorten the flame and confine it for the most part withinthe limits of the combustion chamber.

4. In an oil burner, an air tube having an air inlet in its inner endand an opening in its outer end; a tubular member having a peripheralwall, an inner end wall and an open outer end; said member beingtelescoped in said air tube with its outer end adjacent the outer end ofsaid tube and fitting said opening; the peripheral wall of said memberbeing spaced from the peripheral wall of said tube to form an annularair jacket, which completely surrounds the peripheral wall of saidmember, is closed at its outer end and communicates at its inner endwith the inlet of said tube; an annular disk mounted within and acrossthe tubular member near its inner end and dividing the space within saidmember into inner and outer chambers, a pressure-atomizing nozzlemounted in the inner chamber with its orifice coaxial of and slightlyback of the central opening in said disk to emit through said centralopening into the outer chamber and generally lengthwise thereof a sprayof atomized oil, ignition electrodes mounted in said inner chamberadjacent said nozzle, the peripheral wall of said tubular member havingtherein a circular series of angularlyspaced longitudinally-extendingslots therethrough connecting said jacket to said inner chamber andopening tangentially into such chamber to direct whirling streams of airaround it and thence forwardly to mix with the oil spray near the nozzleand pass out through the central opening in said disk into the outerchamber, the peripheral wall of said member having a plurality of setsof slots therethrough connecting said jacket to the outer chamber, eachset comprising a circular series of angularly-spaced andlongitudinally-extending slots, the slots in each series being angularlystaggered with respect to the slots in the adjacent set, each slotopening through the peripheral wall of said member substantiallytangentially to its inner surface, whereby the air for combustion iswhirled around the outer chamber and around the flame, said slots 11being located to direct whirling streams of air into the outer chambersubstantially from end to end thereof for sweeping the entire innersurface of said peripheral wall, said whirling streams ofairactingtoshortentheilameandconflneittor 5 the most part within thelimits 0 the outer chamber.

JOSEPH A. LOGAN. RICHARD M. COCHRANE.

REFERENCES CITED The following references are of record in the me ofthis patent:

Number 12 UNITED STATES PATENTS Name Date Burg Feb. 92, 1927 Van BruntMar. 10, 1931 Burg Jan. 16, 1934 Saba Oct. 26, 1937 Macrae Apr. 25, 1939DeLancey Nov. 11, 1941 Logan Nov. 12, 1946 Peterson et a1. July 27, 1948Banhorn June 14, 1949

